Protocol processing of, for example, TCP/IP, which is widely used by the Internet and the like, has been conventionally realized mainly by software which operates in a CPU. However, along with an increase in the speed of recent networks, the TCP/IP processing load of CPUs has been increased, and a device realizing high-speed communication by using a TOE (TCP/IP Offload Engine) that carries out TCP/IP processing by dedicated hardware has been proposed.
A TOE is normally controlled by the software which operates in a CPU. However, when the control by the software is taken into consideration, there are problems, for example, that performance of data transmission is not exerted and that disconnection of a session is not normally operated.